Anxiety and mood disorders are among the most prevalent mental disorders in the US, with approximately 21% to 29% of adults meeting diagnostic criteria at some point during their lifetime. Cognitive-behavioral theories, which emphasize the role of thought processes in causing feelings and behaviors, have been integral to our understanding and treatment of these disorders. Cognitive-behavioral theories of obsessive-compulsive disorder, generalized anxiety disorder, and major depressive disorder propose an etiological pathway in which normal intrusive or repetitive negative thoughts (i.e., obsessions, worry, and rumination) are followed by negative interpretations, which lead to engagement in avoidant behavior and to anxiety and mood symptoms. However, these theories have not yet been fully tested using methods appropriate to evaluate the proposed within-person causal processes. Further, theories of each disorder have typically been studied in isolation, despite their similarities. The objective of this application is to test a cognitive-behavioral model of the pathway from normal obsessional, worried, and ruminative thoughts to negative outcomes. Study 1 will use experimental methods to induce negative interpretations of the danger or threat of these common thought types in healthy student participants (N=96). It is hypothesized that individuals randomly assigned to the negative interpretations condition will report increased desire to use avoidant behavior (e.g., thought suppression), as well as increased negative affect, in comparison to individuals who are instructed that these thoughts are meaningless and to individuals who simply report their own interpretations. Study 2 will use experience sampling methodology over a one-week period, asking healthy student participants (N=91) and generalized anxiety disorder-diagnosed community participants (N=40) to report their immediate interpretations of these thought types, their use of avoidance, and their levels of negative affect and overall functioning in daily life. The hypothesis of this study is that negative interpretations of thoughts will predict increased avoidance and negative affect, and decreased functioning, both concurrently and at subsequent reports. Finally, both studies will examine the hypothesis that characteristics of thoughts (e.g., vividness) and of individuals (e.g., preexisting beliefs about thoughts, tendency to experience negative affect) will moderate the proposed relationships between interpretations of thoughts and negative outcomes. This set of findings would be consistent with the cognitive-behavioral model in that negative thought processes are predicted to result in dysfunctional behaviors as well as anxious and depressed mood. PUBLIC HEALTH RELEVANCE: Cognitive-behavioral models suggest that putatively distinct anxiety and mood disorders result from a similar series of within-person causal processes. This study would be the first to use experimental and experience sampling methodology to directly examine these processes across disorders. Findings from this study may contribute to an understanding of common etiological processes across distinct anxiety and mood disorders, and may ultimately lead to the development of more parsimonious etiological models and interventions to treat multiple disorders.